In recent years, a technique has been proposed to assist a driver to drive a vehicle by detecting a point gazed at by the driver and identifying a point, corresponding to the gaze point, on a captured image of a scene around the vehicle.
Japanese Laid-open Patent Publication No. 2009-43003 discloses a drive assist apparatus configured to capture an image of a face of a driver and detect an angle of a line of sight of a right eye of the driver and an angle of a line of sight of a left eye based on the captured image of the face of the driver. Furthermore, the drive assist apparatus detects a line-of-sight vector extending from the center between the left and right eyes to an intersection between a vector indicating the angle of the line of sight of the right eye and a vector indicating the angle of the line of sight of the left eye.
Japanese Laid-open Patent Publication No. 6-189906 discloses an apparatus of detecting a direction of a line of sight configured to detect a direction of a line of sight of a person based on signals output from an eye camera and a 3-dimensional magnetic sensor worn by the person. When the person is seeing a distant point through a windshield, the apparatus of detecting the direction of the line of sight assumes that the point of gaze is at infinity and maps the point of gaze on an image generated by a TV camera capturing an image of a scene in front of the person.
International Publication Pamphlet No. WO 2007/069489 discloses a safety-travel assistance device configured to detect an object to be paid attention to by a driver from two images of a scene in front of a vehicle captured by two cameras. The safety-travel assistance device further determines a relative positional relationship between the vehicle and the object using a triangular method. Furthermore, this safety-travel assistance device detects a direction of a line of sight of a driver, for example, based on a pupil and corneal reflection. In this safety-travel assistance device, a 2-dimensional space is set between the object and the driver, and the object is mapped at a point where a line extending from an eye of the driver to the object intersects the 2-dimensional space. Furthermore, the direction of the line of sight of the driver is mapped into the 2-dimensional space. The safety-travel assistance device detects a relationship between the object and the direction of the line of sight in the 2-dimensional space.